The subject of the present invention is new titanium chelates containing acetylacetone and triethanolamine as chelating agents, as well as solutions of these chelates which are miscible with water.
Chelates of titanium with acetylacetone or triethanolamine are known as titanium acetylacetonate or triethanolamine titanates. In these chelates, two additional alkoxy groups are bound to the central titanium atom. They are generally in the form of solutions in the alcohols corresponding to the alkoxy groups, and are used as catalysts for crosslinking reactions, as coating material, or as adjuvants in the thixotropation of dispersions.
In the areas of application of these known compounds, there is an increasing need for using these reagents in small concentrations, principally in concentrations under 5% by weight, and for replacing the organic solvent largely with water. The obvious solution of this requirement, which is to dilute the above-named alcoholic solutions of these chelates with water, encounters the following difficulties.
If these alcoholic solutions are simply diluted with water, precipitates form. To prevent the occurrence of these precipitates, it has already been proposed, for the preparation of dilute titanium acetylacetonate solutions, to add acetic acid to the solutions prior to the addition of water, then add 13 times the amount of a 1:1 mixture of isopropanol and water, and then dilute them with water. Other proposals are, either first to add twice the amount of methyl ethyl ketone and then slowly stir the water in, or to stir the water in in the form of a mixture of 7 parts water and 3 parts isopropanol. These solvent dilutions, or even the concomitant use of methyl diglycol as solvent, do not, however, lead to a solution of the problem described, since in the course of time, precipitates again form from dilute aqueous solutions prepared in this manner, or they acquire turbidity, and this is undesirable in most applications of the titanium chelates.
The problem therefore was to make titanium chelate preparations available which can be diluted by the addition of water to titanium chelate contents of as little as 1% by weight, while the dilute aqueous solutions obtained are to be stable without the addition of further stabilizers, and are not to become turbid or tend to form precipitates, even after long periods of standing.